MUMBAI, India — The Mumbai slum of Rafiq Nagar has no clean water for its shacks made of ripped tarp and bamboo. No garbage pickup along the rocky, pocked earth that serves as a road. No power except from haphazard cables strung overhead illegally.

And not a single toilet or latrine for its 10,000 people.

Yet nearly every destitute family in the slum has a cell phone. Some have three.

When President Obama visits India on Saturday, he will find a country of startlingly uneven development and perplexing disparities, where more people have cell phones than access to a toilet, according to the United Nations.

It is a country buoyed by a vibrant business world of call centers and software developers, but hamstrung by a bloated, corrupt government that has failed to deliver the barest of services.

Its estimated growth rate of 8.5 percent a year is among the highest in the world, but its roads are crumbling.

And while tens of millions have benefited from India's rise, many more remain mired in some of the worst poverty in the world.

The cell phone frenzy bridges all worlds. Cell phones are sold amid the Calvin Klein and Clinique stores under the soaring atriums of India's new malls, and in the crowded markets of its working-class neighborhoods. Bare shops in the slums sell pre-paid cards for as little as 20 cents next to packets of chewing tobacco, while street hawkers peddle car chargers at traffic lights.

The spartan Beecham's in New Delhi's Connaught Place, one of the country's seemingly ubiquitous mobile phone dealers, is overrun with lunchtime customers of all classes looking for everything from a $790 Blackberry Torch to a basic $26 Nokia.

There were more than 670 million cell phone connections in India by the end of August, a number that has been growing by close to 20 million a month, according to government figures.

Yet U.N. figures show that only 366 million Indians have access to a private toilet or latrine, leaving 665 million to defecate in the open.

“At least tap water and sewage disposal — how can we talk about any development without these two fundamental things? How can we talk about development without health and education?” says Anita Patil-Deshmukhl, executive director of PUKAR, an organization that conducts research and outreach in the slums of Mumbai.

India's leaders say they are sympathetic to the problem.

Prime Minister Manmohan Singh, an economist credited with unleashing India's private sector by loosening government regulation, talks about growth that benefits the masses of poor people as well as a burgeoning middle class of about 300 million. He describes a roaring Maoist insurgency in the east — which feeds in large part on the poor's discontent — as the country's biggest internal security threat.

Sonia Gandhi, chief of the ruling Congress Party, has pushed laws guaranteeing a right to food and education, as well as a gargantuan rural jobs program for nearly 100 million people. But as many as 800 million Indians still live on less than $2 a day, even as Mumbai's stock exchange sits near record highs.

Many fear the situation is unsustainable.

“Everybody understands the threat. Everybody recognizes that there is a gap, that this could be the thing that trips up this country,” says Anand Mahindra, vice chairman and managing director of the Mahindra & Mahindra manufacturing company.

Private companies have tried to fill that gap, and Tata sells a $16 water purifier for the poor. Mafias provide water and electricity to slumdwellers at a cost far higher than what wealthy Indians pay for basic services.

The government is spending $350 million a year to build toilets in rural areas. Bindeshwar Pathak, the founder of the Sulabh Sanitation and Social Reform Movement, estimates the country needs about 120 million more latrines — likely the largest sanitation project in world history.

“Those in power, only they can change the situation,” says Pathak, who claims to have helped build a million low-cost latrines across India over the past 40 years. “India can achieve this — if it desires.”

In the slums of Mumbai, home to more than half the city's population of 14 million, the yearning for toilets is so great that enterprising residents have built makeshift outhouses on their own.

Conditions are far worse in Rafiq Nagar, a crowded, 15-year-old slum on the lip of a 110-acre garbage dump.

Most of the slumdwellers are ragpickers who sort through heaps of trash for scraps of plastic, glass, metal, even bones, anything they can sell to recyclers for cash.

A pungent brew of ripe garbage and sewage blows through the trash-strewn streets, as choking smoke from wood fires rolls out the doorways of windowless huts.

Since there are no water pipes or wells here, residents are forced to rely on the water mafia for water for cooking, washing clothes, bathing and drinking.

“If the government would give us water, we would pay that money to the government,” said Suresh Pache, 41, a motorized rickshaw driver.

Yet the world of technology has embraced the slumdwellers with its cheap cell phones and cut-rate calling plans that charge a sliver of a penny a minute.

Pache bought his first phone for $31 four months ago. Since then, his wife, a ragpicker, found two other broken models as she scoured the garbage dump, and he paid to have them repaired.

He speaks with fluency about the different plans offered by Tata, Reliance and Idea that cost him a total of $6.70 a month. Now, when his rickshaw breaks down, he can alert his wife with a call. She uses her phone to tell the recyclers where she is in the dump so they can drive out to her, saving her the time and effort of dragging her bag of scraps to them.

In fact, the spread of cell phones may end up bringing toilets.

R. Gopalakrishnan, executive director of Tata Sons, one of India's most revered companies, says the rising aspirations of the poor, buttressed by their growing access to communications and information, will put tremendous pressure on the government to start delivering.

People already are starting to challenge local officials who for generations answered to no one, he says.